How old is to old

[Dohboy]

I have some yeast that I washed and has been in the fridge for about 12 months, will it be ok to use??

 

[amc22]

Make a starter and find out.

 

[Dohboy]

Make a starter and find out.

But how will I know if it any good, this will be the first time making a starter so what do I look for? Ps I have just made a stir plate.

 

[JonM]

Measure the starter wort gravity before pitching. Then check again after 3-4 days and see if it's changed. Also, you may (but might not) see a krausen.

 

[william_shakes_beer]

If you get a layer of white yeast at the bottom of the starter container its good. If the yeast is old it may take longer to start, since there will be fewer viable cells and more reproduction wil need to take place. Remember, there are some on this site that selectively store single cells of yeast on plates for freezing. In theory you only need one cell, although in reality bacteria (which is present even with the strictest sanitization practices) will outcompete the yeast ig sucfficient cells are not initially available.